Serine proteases and brain damage - is there a link?

The protective blood-brain barrier normally allows diffusion of small molec ules such as oxygen and carbon dioxide, and transport of essential nutrient s, but excludes large proteins and other blood constituents from the inters titial space of the CNS. However, head trauma, stroke, status epilepticus a nd other pathological conditions can all compromise the integrity of this b arrier, and allow blood proteins as large as albumin to gain access to the extracellular spaces that surround neurons and glia. Given their possible e ntry into brain tissue during cerebrovascular insult, the effects of blood- derived proteases such as thrombin, tissue plasminogen activator and plasmi n in the CNS have come under increasing scrutiny. Evidence now supports a r ole for serine proteases in the sequence of events that can lead to glial s carring, edema, seizure and neuronal death.